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Periventricular morphology in the diencephalon of antarctic notothenioid teleosts
Author(s) -
Lannoo Michael J.,
Eastman Joseph T.
Publication year - 1995
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903610108
Subject(s) - biology , neuropil , subependymal zone , diencephalon , third ventricle , operculum (bryozoa) , anatomy , cerebrospinal fluid , subcommissural organ , ventricular system , neuroscience , zoology , central nervous system , genus
We have examined the subependymal region of the diencephalic third ventricle in notothenioid perciforms and report a pattern of neuropil expansions that appears to be phyletically derived for notothenioids and their outgroups but that is otherwise unique among vertebrates. We recognize five types of expansions based on their composition (from less dense neuropil to sacs) and width or protrusion into the third ventricle. In the species with the most elaborate morphology, Trematomus bernacchii , bilateral subependymal expansions fuse along the midline to form a single sac within the ventricular cavity. The extent of these expansions loosely corresponds with phyletic position but also (and perhaps more importantly) is correlated with the habitation of cold water (r 2 = 0.48; P = 0.012). Furthermore, subependymal expansion type is positively correlated with the maximum size of the soma of neurons in two hypothalamic nuclei, the preopticus magnocellularis (r 2 = 0. 54; P = 0. 006) and the lateralis tuberis (r 2 = 0.40; P = 0.038). These nuclei project to the pituitary and contain cerebrospinal fluid‐contacting neurons. In considering the functional consequences of this morphology, we cannot dismiss the possibility that these structures form a specialized enteroceptive system tied to the monitoring of cerebrospinal and extracellular fluid components, including antifreeze glycopeptides and inorganic ions. © 1995 Wiley‐Liss, Inc.